Wired keyboards proven to be vulnerable. Someone could be reading the magnetic waves coming from the keyboard as you type. Two students of the EPFL in Switzerland experimented. Using 11 keyboards they concluded that all 11 are vulnerable to at least one of the four attacks tested.
This article provides additional detail to the previously reported findings. You can find the original article written by Peter Suciu here.
How does it work?
Martin Vuagnoux and Sylvain Pasini two students at the computer science lab of EPFL (Security and Cryptography Laboratory in Lausanne) experimented and found the following.
What do you usually type on your keyboard? Passwords to access all online accounts and bank accounts. These passwords could be intercepted. They are able to decode the Electromagnetic Emanations of the keyboard from a distance of 20m (65.6 feet) and even from another room.